Signal Modification Method for Efficient Coding of Speech Signals

1. A method, comprising: dividing a sound signal into a series of successive flames; dividing each frame into a number of subframes; producing, by a device, a residual signal by filtering the sound signal through a linear prediction analysis filter; locating a last pitch pulse of the sound signal of a previous frame from the residual signal; extracting a pitch pulse prototype of given length around a position of the last pitch pulse of the previous frame using the residual signal; locating pitch pulses in a current frame using the pitch pulse prototype; predicting a position of a first pitch pulse of the current frame to occur at an instant related to the position of the previously located pitch pulse and an interpolated open-loop pitch estimate at an instant corresponding to the position of the previously located pitch pulse; and refining the predicted position of said pitch pulse by maximizing a weighted correlation between the pulse prototype and the residual signal.

2. The method as defined in claim 1 , further comprising: repeating the prediction of pitch pulse position and the refinement of predicted position until said prediction and refinement yields a pitch pulse position located outside the current frame.

3. An apparatus, comprising: a divider, within a device, configured to divide a sound signal into a series of successive frames; a divider of each frame into a number of subframes; a linear prediction analysis filter configured to filter the sound signal and thereby producing a residual signal; a detector configured to detect a last pitch pulse of the sound signal of a previous frame in response to the residual signal; an extractor configured to extract a pitch pulse prototype of given length around a position of the last pitch pulse of the previous frame in response to the residual signal; a detector configured to detect pitch pulses in a current frame using the pitch pulse prototype; a predictor configured to predict a position of each pitch pulse of the current frame to occur at an instant related to the position of the previous located pitch pulse and an interpolated open-loop pitch estimate at said instant corresponding to the position of the previously located pitch pulse; and a refiner configured to refine the predicted position of said pitch pulse by maximizing a weighted correlation between the pulse prototype and file residual signal.

4. The apparatus as defined in claim 3 , further comprising: a repeater configured to repeat the prediction of pitch pulse position and the refinement of predicted position until said prediction and refinement yields a pitch pulse position located outside the current frame.

5. A method, comprising: dividing, by a device, a sound signal into a series of successive frames; dividing each frame into a number of subframes; producing a weighted sound signal by processing the sound signal through a weighting filter, the weighted sound signal being indicative of signal periodicity; locating a last pitch pulse of the sound signal of the previous frame from the weighted sound signal; extracting a pitch pulse prototype of given length around a position of the last pitch pulse of a previous frame using the weighted sound signal; locating pitch pulses in a current frame using the pitch pulse prototype; predicting a position of a first pitch pulse of the current frame to occur at an instant related to the position of the previously located pitch pulse and an interpolated open-loop pitch estimate at an instant corresponding to the position of the previously located pitch pulse; and refining the predicted position of said pitch pulse by maximizing a weighted correlation between the pulse prototype and the weighted sound signal.

6. The method as defined in claim 5 , further comprising: repeating the prediction, of pitch pulse position and the refinement of predicted position until said prediction and refinement yields a pitch pulse position located outside the current frame.

7. An apparatus, comprising: a divider, within a device, configured to divide a sound signal into a series of successive frames; a divider of each frame into a number of subframes; a weighting filter configured to process the sound signal to produce a weighted sound signal, the weighted sound signal being indicative of signal periodicity; a detector configured to detect a last pitch pulse of the sound signal of a previous frame in response to the weighted sound signal; an extractor configured to extract a pitch pulse prototype of given length around a position of the last pitch pulse of the previous frame in response to the weighted sound signal; a detector configured to detect pitch pulses in a current frame using the pitch pulse prototype; a predictor configured to predict a position of each pitch pulse of the current frame to occur at an instant related to the position of the previous located pitch pulse and an interpolated open-loop pitch estimate at said instant corresponding to the position of the previously located pitch pulse; and a refiner configured to refine the predicted position of said pitch pulse by maximizing a weighted correlation between the pulse prototype and the weighted sound signal.

8. The apparatus as defined in claim 7 , further comprising: a repeater configured to repeat the prediction of pitch pulse position and the refinement of predicted position until said prediction and refinement yields a pitch pulse position located outside the current frame.

9. A method, comprising: dividing, by a device, a sound signal into a series of successive frames; dividing each frame into a number of subframes; producing a synthesized weighted sound signal by filtering a synthesized speech signal produced during a last subframe of a previous frame of the sound signal through a weighting filter; locating a last pitch pulse of the sound signal of the previous frame from the synthesized weighted sound signal; extracting a pitch pulse prototype of given length around the position of the last pitch pulse of the previous frame using the synthesized weighted sound signal; locating pitch pulses in a current frame using the pitch pulse prototype; predicting a position of a first pitch pulse of the current frame to occur at an instant related to the position of the previously located pitch pulse and an interpolated open-loop pitch estimate at an instant corresponding to the position of the previously located pitch pulse; and refining the predicted position of said pitch pulse by maximizing a weighted correlation between the pulse prototype and the synthesized weighted sound signal.

10. The method as defined in claim 9 , further comprising: repeating the prediction of pitch pulse position and the refinement of predicted position until said prediction and refinement yields a pitch pulse position located outside the current frame.

11. An apparatus, comprising: a divider, within a device, configured to divide a sound signal into a series of successive frames; a divider configured to divide each frame into a number of subframes; a weighting filter configured to filter a synthesized speech signal produced during a last subframe of a previous frame of the sound signal and thereby producing a synthesized weighted sound signal; a detector configured to detect a last pitch pulse of the sound signal of the previous frame in response to the synthesized weighted sound signal; an extractor configured to extract a pitch pulse prototype of given length around the position of the last pitch pulse of the previous frame in response to the synthesized weighted sound signal; a detector configured to detect pitch pulses in a current frame using the pitch pulse prototype; a predictor configured to predict a position of each pitch pulse of the current frame to occur at an instant related to the position of the previous located pitch pulse and an interpolated open-loop pitch estimate at said instant corresponding to the position of the previously located pitch pulse; and a refiner configured to refine the predicted position of said pitch pulse by maximizing a weighted correlation between the pulse prototype and the synthesized weighted sound signal.

12. The apparatus as defined in claim 11 , further comprising: a repeater configured to repeat the prediction of pitch pulse position and the refinement of predicted position until said prediction and refinement yields a pitch pulse position located outside the current frame.